Enhanced 1,4-Butanediol de Novo Synthesis in Yarrowia lipolytica by Incorporating Dynamic Regulation of Thiamine.

Abstract

1,4-Butanediol (1,4-BDO), one of the most important platform diols, has been widely utilized as a comonomer to manufacture several million tons of polymers every year. Microbial synthesis of the non-natural 1,4-BDO is extremely challenging. Although several artificial routes have been proposed and applied in Escherichia coli, among them, the branching metabolic flux from α-ketoglutarate (α-KG) to the artificial route was considered the most thermodynamically efficient solution. Establishing a 1,4-BDO synthesis route in Yarrowia lipolytica, a native α-KG and succinate hyperproducer, should have high potential. A CoA-dependent 1,4-BDO synthesis route was introduced into Y. lipolytica, followed by the investigation of rate-limiting steps, optimization of the thiamine dosage, improvement of the precursor and cofactor availability, and deletion of the competition step. It was illustrated that 1,4-BDO synthesis was susceptible to metabolic throughput of the GABA-succinate shunt and NADPH availability. Also, there was a trade-off between cellular growth and 1,4-BDO synthesis. A combinational strategy, in which hereditary dynamic regulation of thiamine was incorporated into those positive metabolic modifications, was implemented, and 6217.1 mg·L^-1 1,4-BDO was achieved under the batch fermentation model. This work also demonstrated the high potential and capacity for biosynthesis of non-nature chemicals from TCA intermediates in the yeast cells, and provided a novel clue to rebalance the metabolic flux between the heterologous pathway and central metabolism.